Mahathir says Najib misused his power by trying to smother investigations into both these scandals.

Embattled Malaysian Prime Minister Najib Razak suffered another jolt on Wednesday with former prime minister Mahathir Mohamad filing a lawsuit accusing him of corruption and abuse of power.

In his latest effort to remove Najib from office, Mahathir cites the corruption scandal plaguing 1 Malaysia Development Berhad and the personal donation Najib received from overseas.

Mahathir says Najib misused his power by trying to smother investigations into both these scandals.

The lawsuit alleges that Najib took various deliberate steps in bad faith to "obstruct, interfere, impede and derail" various investigations and inquiries.

In the lawsuit, Mahathir requests action to "reverse the destruction of the rule of law and the sanctity of the provision of our Federal Constitution", the Malay Mail reported.

Apart from Mahathir, the country's longest serving prime minister, two other former members of the ruling United Malay National Organisastion (Umno) party are also part of the move to approach the court against Najib.

The suit was filed in the Kuala Lumpur High Court. The plaintiffs ask the court to extract damages of RM2.6 billion and aggravated damages of RM42 million from the prime minister.

Najib has consistently denied any wrongdoing and said the funds deposited into his account was a personal donation from the Saudi royal family and that the amount was returned to the Saudis..

Though Attorney-General Mohamed Apandi cleared Najib of any wrongdoing, saying the money deposited in the prime minister's bank account was entirely legal "personal donation" from the Saudi royal family, the Saudi's clarified last week the amount was not personal donation.